Publications by authors named "Julie A Johnson"

Chronic pain is a prevalent condition with enormous economic burden. Opioids such as tramadol, codeine, and hydrocodone are commonly used to treat chronic pain; these drugs are activated to more potent opioid receptor agonists by the hepatic CYP2D6 enzyme. Results from clinical studies and mechanistic understandings suggest that CYP2D6-guided therapy will improve pain control and reduce adverse drug events.

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  • Warfarin dosing is affected by individual clinical and genetic factors, with a need to explore genetic variants specific to African populations for better dosing guidance.
  • A genome-wide association study (GWAS) focused on 989 warfarin-treated participants from Uganda, South Africa, and Zimbabwe, as well as African American cohorts, found significant genetic variants associated with warfarin response.
  • The study highlighted the importance of the CYP2C9 and VKORC1 genes and identified a new potential genetic locus (MALL) that may impact warfarin response, warranting further research to understand its biological relevance.
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Background: Cytochrome P450 2C19 (CYP2C19) intermediate and poor metabolizer patients exhibit diminished clopidogrel clinical effectiveness after percutaneous coronary intervention (PCI). However, outcome studies to date have lacked racial diversity. Thus, the impact of genotype on cardiovascular outcomes in patients treated with clopidogrel who identify as Black or African American remains unclear.

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  • SSRIs' metabolism is significantly affected by the pharmacogenes CYP2D6 and CYP2C19, which influences how effective these medications might be for treating depression in patients.
  • A clinical trial is being conducted to assess whether using genetic testing to guide the selection and dosing of antidepressants can provide better control of depression symptoms in individuals aged 8 and older.
  • The trial includes two groups: one gets pharmacogenetic testing and support immediately, while the other group is tested after 6 months, with the main outcome measured being changes in depression scores after three months.
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Hydrocodone, tramadol, codeine, and oxycodone are commonly prescribed opioids that rely on activation by cytochrome P450 2D6 (CYP2D6). CYP2D6 inhibitors can significantly decrease CYP2D6 activity, leading to reduced generation of active metabolites, and impairing pain control. To understand this impact, we assessed emergency department (ED) visits in patients initiating these CYP2D6-dependent opioids while on CYP2D6-inhibitor antidepressants vs.

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Hypertensive patients with a higher proportion of genetic West African ancestry (%GWAA) have better blood pressure (BP) response to thiazide diuretics (TDs) and worse response to β-blockers (BBs) than those with lower %GWAA, associated with their lower plasma renin activity (PRA). TDs and BBs are suggested to reduce BP in the long term through vasodilation via incompletely understood mechanisms. This study aimed at identifying pathways underlying ancestral differences in PRA, which might reflect pathways underlying BP-lowering mechanisms of TDs and BBs.

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Background: An ABCD-GENE (age, body mass index, chronic kidney disease, diabetes, and CYP2C19 genetic variants) score ≥10 predicts reduced clopidogrel effectiveness, but its association with response to alternative therapy remains unclear.

Objectives: The aim of this study was to evaluate the association between ABCD-GENE score and the effectiveness of clopidogrel vs alternative P2Y inhibitor (prasugrel or ticagrelor) therapy after percutaneous coronary intervention (PCI).

Methods: A total of 4,335 patients who underwent PCI, CYP2C19 genotyping, and P2Y inhibitor treatment were included.

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Background: Thiazide diuretics are the second most frequently prescribed class of antihypertensives, but up to 50% of patients with hypertension have minimal antihypertensive response to thiazides. We explored circulating microRNAs (miRNAs) in search of predictive biomarkers of thiazide response.

Methods And Results: We profiled 754 miRNAs in baseline plasma samples of 36 hypertensive European American adults treated with hydrochlorothiazide, categorized into responders (n=18) and nonresponders (n=18) on the basis of diastolic blood pressure response to hydrochlorothiazide.

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Proton pump inhibitors (PPIs) are commonly used medications to treat acid-related conditions, including gastro-esophageal reflux disease (GERD). Gastroenterology guidelines mention the importance of CYP2C19 in PPI metabolism and the influence of genetic variations on variable responses to PPIs, but do not currently recommend the genotyping of prior to prescribing PPIs. There are strong data to support the influence of genetic variations on the pharmacokinetics of PPIs and clinical outcomes.

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Swen et al. examine the utility of multi-gene pharmacogenetic testing in a large multi-national cohort. They show fewer adverse drug reactions among patients receiving testing and prescribing recommendations based on genotype results compared with those receiving usual care.

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Introduction: CYP2D6 contributes to the metabolism of approximately 20-25% of drugs. However, is highly polymorphic and different alleles can lead to impacts ranging from null to increase in activity. Moreover, there are commonly used drugs that potently inhibit the CYP2D6, thus causing 'phenoconversion' which can convert the genotypic normal metabolizer into phenotypic poor metabolizer.

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Black patients suffer worse outcomes after percutaneous coronary intervention (PCI) than White patients. Inequities in antiplatelet prescribing may contribute to this health disparity. We compared P2Y inhibitor prescribing by race following CYP2C19 genotyping to guide antiplatelet therapy selection after PCI.

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This study conducted a pairwise comparison of antihypertensive and metabolic effects of hydrochlorothiazide (HCTZ) and chlorthalidone (CTD) at 25 mg/day in the same individuals to address the clinical dilemma on preferred thiazide for hypertension (HTN) management. We included 15 African American (AA) and 35 European American (EA) patients with HTN treated with HCTZ and CTD as part of the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) and PEAR-2 trials, respectively. Mean reduction in systolic/diastolic blood pressure (SBP/DBP) with HCTZ versus CTD was 8/5 versus 16/8 mmHg among EA patients (p < 1.

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  • The study investigates genetic variants linked to early-onset ischemic stroke (EOS) in individuals aged 18-59, contrasting with previous research focused on late-onset stroke (LOS).
  • Researchers conducted a meta-analysis involving 16,730 EOS cases and 599,237 controls to identify significant genetic associations and compared results between EOS and LOS.
  • Findings include two genetic variants associated with blood subgroups that show a stronger connection to EOS than LOS, indicating that genetic factors promoting blood clotting are particularly influential in early-onset cases.
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Patients with higher genetic West African ancestry (GWAA) have hypertension (HTN) that is more difficult to treat and have higher rates of cardiovascular diseases (CVD) and differential responses to antihypertensive drugs than those with lower GWAA. The mechanisms underlying these disparities are poorly understood. Using data from 84 ancestry-informative markers in US participants from the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) and PEAR-2 trials, the GWAA proportion was estimated.

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Opioid prescribing for postoperative pain management is challenging because of inter-patient variability in opioid response and concern about opioid addiction. Tramadol, hydrocodone, and codeine depend on the cytochrome P450 2D6 (CYP2D6) enzyme for formation of highly potent metabolites. Individuals with reduced or absent CYP2D6 activity (i.

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Hypertension is a leading risk factor for cardiovascular disease mortality. African Americans (AAs) have the highest prevalence of hypertension in the United States, and to alleviate the burden of hypertension in this population, better control of blood pressure (BP) is needed. Previous studies have shown considerable interpersonal differences in BP response to antihypertensive treatment, suggesting a genetic component.

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  • The study investigates the role of specific genetic variants (SNPs) in the PPARGC1A gene on the risk of subsequent coronary heart disease (CHD) events in patients already diagnosed with the condition.* -
  • Using data from 23 studies with nearly 81,000 participants, the researchers analyzed associations between three SNPs and the occurrence of CHD death or myocardial infarction, employing a Cox proportional hazards model.* -
  • The meta-analysis found no significant links between the genetic variants and the risk of subsequent CHD events or cardiovascular diseases, except for some inverse associations observed in specific participant subgroups.*
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Rationale And Objective: APOL1 risk alleles are associated with increased cardiovascular and chronic kidney disease (CKD) risk. It is unknown whether knowledge of APOL1 risk status motivates patients and providers to attain recommended blood pressure (BP) targets to reduce cardiovascular disease.

Study Design: Multicenter, pragmatic, randomized controlled clinical trial.

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There are limited comparison data throughout the dosing interval for generic versus brand metoprolol extended-release (ER) tablets. We compared the pharmacokinetics (PKs) and pharmacodynamics of brand name versus two generic formulations (drugs 1 and 2) of metoprolol ER tablets with different time to maximum concentration (T ) in adults with hypertension. Participants were randomized to equal drug doses (50-150 mg/day) administered in one of two sequences (brand-drug1-brand-drug2 or brand-drug2-brand-drug1) and completed 24-h PK, digital heart rate (HR), ambulatory blood pressure (BP), and HR studies after taking each formulation for greater than or equal to 7 days.

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MicroRNAs are small noncoding RNAs with potential regulatory roles in hypertension and drug response. The presence of many of these RNAs in biofluids has spurred investigation into their role as possible biomarkers for use in precision approaches to healthcare. One of the major challenges in clinical translation of circulating miRNA biomarkers is the limited replication across studies due to lack of standards for data normalization techniques for array-based approaches and a lack of consensus on an endogenous control normalizer for qPCR-based candidate miRNA profiling studies.

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The Age, Body mass index, Chronic kidney disease, Diabetes mellitus, and CYP2C19 GENEtic variants (ABCD-GENE) score was developed to identify patients at risk for diminished antiplatelet effects with clopidogrel after percutaneous coronary intervention (PCI). The objective of this study was to validate the ability of the ABCD-GENE score to predict the risk for atherothrombotic events in a diverse, real-world population of clopidogrel-treated patients who underwent PCI and received clinical CYP2C19 genotyping to guide antiplatelet therapy. A total of 2,341 adult patients who underwent PCI, were genotyped for CYP2C19, and received treatment with clopidogrel across four institutions were included (mean age 64 ± 12 years, 35% women, and 20% Black).

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Background Studies have demonstrated increased risk of major atherothrombotic events in loss-of-function (LOF) variant carriers versus non-carriers treated with clopidogrel after percutaneous coronary intervention (PCI). We sought to evaluate real-world outcomes with the clinical implementation of -guided antiplatelet therapy after PCI. Methods and Results Data from 9 medical centers where genotyping was performed in the setting of PCI were included.

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Pharmacogenetic dosing improves the accuracy of warfarin dosing, but current pharmacogenetic dosing algorithms are less accurate in populations of African ancestry. The cytochrome P450 2C9*5 (CYP2C9*5) allele is found almost exclusively in populations of African ancestry, and in vitro studies suggest CYP2C9*5 is associated with reduced clearance of warfarin. The clinical relevance of this single-nucleotide variation (SNV) (formerly SNP) is uncertain.

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CYP2C19 catalyzes the bioactivation of the antiplatelet prodrug clopidogrel, and CYP2C19 genotype impacts clopidogrel active metabolite formation. CYP2C19 intermediate and poor metabolizers who receive clopidogrel experience reduced platelet inhibition and increased risk for major adverse cardiovascular and cerebrovascular events. This guideline is an update to the 2013 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for the use of clopidogrel based on CYP2C19 genotype and includes expanded indications for CYP2C19 genotype-guided antiplatelet therapy, increased strength of recommendation for CYP2C19 intermediate metabolizers, updated CYP2C19 genotype to phenotype translation, and evidence from an expanded literature review (updates at www.

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